| 1 | Petals present (scars visible under the fruit) |
| 1' | Petals absent or only 1 or 2 present |
| 2 | Ovary 3-locular. Twigs fairly persistently angular. Leaflets bullate, the apex emarginate, rounded or obtuse |
| 2' | Ovary 2-locular. Twigs terete. Leaflets flat, the apex acutely acuminate 3. S. bilocularis 3a. Leaflets 7-20 by 3-6 cm, flat, the apex tapering into a broad rounded acumen. Lowland |
| 2'' | Leaflets 4.5-8 by 1.5-3.5 cm, ± bullate, the apex emarginate, rounded, or obtuse. Montane |
